1. Field of the Invention
The present invention relates to a digital broadcasting system and a data processing method thereof, and more particularly, to a digital broadcasting system and a data processing method which can reduce waste of frequency resources, via efficient transmission and reception of packets.
2. Description of the Related Art
Recently, the type of a television (TV) broadcasting has been rapidly changing over from analog to digital, and satellite broadcasting systems such as Koreasat in Korea, DirecTV in the United States, SKY PerfecTV! in Japan, and others, have already adopted digital television (DTV) systems. In terrestrial broadcasting, ATV (Advanced TV) in the United States, and DVB (Digital Video Broadcasting) in Europe have rapidly propelled the advance of digital TV broadcasting.
FIG. 1 illustrates a typical digital TV broadcasting system and a process of transmitting a TV program from a broadcasting station to a base station. Referring to FIG. 1, a digital TV broadcasting system 100 includes at least a broadcasting station 110 and multiple base stations 120A-120N arranged within different coverage areas. The broadcasting station 110 generates a broadcasting signal in the form of packets by compressing and packetizing video and audio signals obtained through, for example, a camera and a microphone, respectively, using a modulator (not shown), and transmits the broadcasting packets, via a transmission channel (e.g., optical cables or wireless). The respective base stations 120A-120N, which may be located in different parts of the country, are arranged to receive the broadcast signal for processing accordingly. Each base station is typically provided with a transceiver (i.e., a transmitter and a receiver) capable of transmitting and receiving the broadcast signal.
In this case, broadcast packets are sequentially transmitted one by one. A transmitter, which is installed in a respective base station, processes the broadcast packet transmitted from the broadcasting station 110 in the unit of a frame, and transmits the processed broadcast signal to broadcast receivers, such as TV receivers that belong to a predetermined communication area. Here, the respective base stations 120A-120N have fixed transmission ranges in which broadcast signals can be transmitted, respectively.
Such broadcast packets or frames may be provided in diverse forms. When frames are generated in a transmitter of the respective base station 120A-120N, the transmitter forms the frames by successively accumulating the transmitted broadcast packets. However, if the transmitter is in an “OFF” state, the transmitter cannot receive the broadcast packets, even though the broadcast packets are transmitted from the broadcasting station 110. When the transmitter is turned “ON”, frames are formed by accumulating the received broadcast packets. Accordingly, the respective base stations 120A-120N may receive broadcast packets in different orders depending on the “ON/OFF” state of the transmitters, and in this case, the broadcast packets included in one frame may differ for the respective base stations 120A-120N.
As the transmitters of the respective base stations 120A-120N receive the broadcast packets in different orders, the frames formed through the respective base stations 120A-120N are not identical. Accordingly, in an area where the same broadcast signals are received from two or more base stations 120A-120N, interference may occur between the broadcast signals. As a result, the broadcast signal may not be received at a broadcast receiver.
To prevent this type of interference, the respective base stations 120A-120N generally use separate channels, i.e., different frequencies. In the case of using a single frequency, a method of preventing the overlapping of communication ranges of the respective base stations 120A-120N has been used in order to prevent the broadcast signals from being received from two or more base stations 120A-120N. However, in the case where the respective base stations 120A-120N use separate channels, frequency resources can be wasted. In addition, in the case of preventing the overlapping of the communication ranges of the respective base stations, areas where broadcast receivers cannot receive any of the broadcast signals from the respective base stations 120A-120N may occur inevitably.
Accordingly, a new technique is required to prevent waste of frequency resources by making the respective base stations 120A-120N use the same channel and prevent the occurrence of any area where the broadcast signals cannot be received.